pull the powervalve apart, clean the valve carefully with laquer thinner or equivelant. the most common reasons for a powervalve to stick. 1. poor quality 2-cycle oil (use a brand of 2-cycle oil that contains mineral oil, synthetic blend or both mineral oil and synthetic, such as legend zx2 two cycle oil. 2. use higher octane fuel. using a higher octane fuel will prevent the powervalve from sticking. 3. use (sea foam) found at your local auto parts store or hardware store.